This application claims the priority of German patent document 198 15 715.0, filed Apr. 8, 1998, the disclosure of which is expressly incorporated by reference herein.
The invention relates to an electronic vehicle controller which includes a processor unit and a communication output stage for coupling the controller to a databus.
Controllers of the generic type are used in particular in modern automobiles using data networks for the vehicle electronics. In this case, the various electronic controllers used in the automobile are connected to a databus (generally, a so-called CAN bus) for data communication with one another, and potentially with peripheral units. As is normal for electronic data processing, the data interchange is carried out using suitable protocols for the data which, in this specialized field, means the time sequence in which data information is transferred. A controller interchanges data of various types relating to measured values, switch positions etc. with other controllers via communication links, using an associated data protocol. At the same time, if required, it communicates with other components, such as sensors, actuators, display or indicator elements and interfaces to other communication channels, such as mobile radio etc. It is thus necessary to have a plurality of different protocols available in the controller.
Normally, an appropriate number of different, predefined protocols are permanently implemented in the vehicle controller in order to satisfy this requirement. For this purpose, the protocols for the controller are configured in the desired manner (in terms of the data identification and data representation) during the design phase of the associated data network system. Once the definition has been carried out in this way, the controller protocols for interchanging data can no longer be modified externally.
In view of these considerations, all the desired functionalities of the controller must conventionally, be defined in an early development phase. Any change to the functionality which is accompanied by a change to the protocols for the data interchange, and is implemented in a late development phase of a controller or after completion of its development, is linked with a high cost. Even minor differences between two controller functionalities require the development of two controllers, to take account of these differences, from the start.
It is furthermore known for vehicle controllers which can be coupled to a databus to be equipped with converters for signal communication via the respective databus, so that a controller can be variably coupled to different databus types, see, for example, German patent documents DE 41 40 803 A1 and DE 42 29 931 A1.
The invention is based on the technical problem of providing an electronic vehicle controller of the type mentioned initially, in which changes to protocols for interchanging data with other controllers via an appropriate databus can be implemented even during a late development phase or after completion of development of the controller, at low cost.
This and other objects and advantages are achieved by the electronic vehicle controller according to the invention, which contains a data protocol device situated between the processor unit and communication output stage. This protocol device variably defines the respective data protocol that is to be used at the moment for the data transfer, as a function of protocol control information, which is supplied to it, selecting from a predeterminable number of different data protocols. The functionality of this universal data protocol device can thus be modified via associated configuration control inputs to it, even at the end of the development process for the controller. Thus, its functionalities need not all be defined in an early development phase. Furthermore, data protocol changes which are required for a variant of an existing controller can be implemented by appropriately changing or reconfiguring the protocols in the data protocol device without necessity of developing the controller variant as a specific component, on its own.
In one embodiment of the invention the data protocol device contains a transmission block which can transpose data received from the processor unit via a specific number of data input channels, to a possibly different number of data output channels (using, for example a suitable transmission multiplexer stage), with the associated data protocol being variably adjustable. The data which may be emitted on a number of channels from the processor unit can thus be transposed using any desired protocol, to any required predetermined number of output channels, and can be passed on to the databus. In order to control data transmission in the downstream components, the transmission multiplexer stage emits a data transmission control signal, which is a function of the data protocol, at a control signal output.
In a further refinement, the transmission block of the data protocol device contains an overload protection unit, to which the data transmission control signal (which is a function of the data protocol) of the transmission multiplexer stage is supplied, and which passes this signal on (which may be modified) in such a manner that the downstream communication output stage is protected against an excessive number of transmission processes.
In another embodiment of the invention, the data protocol device contains a reception block of a design equivalent to that of the transmission block mentioned above. The reception block transposes data which arrive via data input channels on the bus side, to corresponding data output channels on the processor side, using a suitable data protocol. For this purpose, a reception multiplexer stage is provided which, inter alia, receives an associated data reception control signal. If the transmission block is also present, the universal data protocol device operates bidirectionally.
In a further refinement, the data protocol device contains an obsolescence unit in the reception block which receives the data reception control signal, and can use it to confirm the existence of a situation in which no more data is arriving, although such data is still expected. It then emits an appropriate information signal to the reception multiplexer stage.
According to another feature of the invention, the transmission and/or the reception block of the data protocol device contain a so-called history register (a shift register or buffer unit) which suppresses redundant transmission and/or reception processes. In the transmission block, there is in each case one history register per data input channel upstream of the transmission multiplexer stage. In the reception block, it is arranged downstream of the reception multiplexer stage, per data output channel. In a further refinement of the invention, the respective history register is assigned an assessment unit, which characterizes the amount of input data and contains any required selectable assessment functions.
A data protocol device according to the invention contains a so-called multimode timer which is assigned to the respective transmission and/or reception multiplexer stage and, as a function of the selected data protocol, produces a clock signal for cyclic transmission and/or reception of signals for the transmission and/or reception multiplexer stage. In this manner, cyclic transmission and reception are possible, without having to wait for a transmission and/or reception termination signal.